U.S. patent application number 11/034021 was filed with the patent office on 2005-08-25 for method and apparatus for testing for the quality of a light transmitting/receiving structure.
This patent application is currently assigned to Delta Electronics, Inc.. Invention is credited to Deng, Wei-Ming, Kuu, Wien-Haurn, Lin, Di-Kuan.
Application Number | 20050184227 11/034021 |
Document ID | / |
Family ID | 34859741 |
Filed Date | 2005-08-25 |
United States Patent
Application |
20050184227 |
Kind Code |
A1 |
Kuu, Wien-Haurn ; et
al. |
August 25, 2005 |
Method and apparatus for testing for the quality of a light
transmitting/receiving structure
Abstract
In a test method, an end of a testing optical fiber is first
coupled to a light transmitting/receiving structure. The testing
optical fiber and the light transmitting/receiving structure are
then fixed, and the testing optical fiber is passed through the
opening of a defining structure. Next, the testing optical fiber is
moved within a testing zone defined by the opening, and variations
of the strength of an optical signal transmitted in the testing
optical fiber are measured. Finally, the quality of the light
transmitting/receiving structure is judged according to the
variations. The test apparatus includes the securing structure, the
defining structure, and a testing structure.
Inventors: |
Kuu, Wien-Haurn; (Taoyuan
Hsien, TW) ; Deng, Wei-Ming; (Taoyuan Hsien, TW)
; Lin, Di-Kuan; (Taoyuan Hsien, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Delta Electronics, Inc.
|
Family ID: |
34859741 |
Appl. No.: |
11/034021 |
Filed: |
January 13, 2005 |
Current U.S.
Class: |
250/227.14 |
Current CPC
Class: |
G01J 1/08 20130101; G02B
6/385 20130101; G02B 6/421 20130101; G01J 2001/4247 20130101; G02B
6/3807 20130101; G02B 6/4292 20130101 |
Class at
Publication: |
250/227.14 |
International
Class: |
G01J 001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2004 |
TW |
93104822 |
Claims
What is claimed is:
1. A method of testing for the quality of a light
transmitting/receiving structure, said method comprising: coupling
an end of a testing optical fiber to said light
transmitting/receiving structure; fixing said testing optical fiber
and said light transmitting/receiving structure and passing said
testing optical fiber through a testing zone, wherein an optical
signal transmission path of said light transmitting/receiving
structure is coaxially positioned with said testing zone; moving
said testing optical fiber within said testing zone and measuring
variations of the strength of an optical signal transmitted in said
testing optical fiber; and judging the quality of the light
transmitting/receiving structure according to said variations.
2. The method of claim 1, wherein the step of moving said testing
optical fiber within said testing zone comprises moving said
testing optical fiber up and down, right and left, or forward and
backward, or moving said testing optical fiber clockwise or
counterclockwise around the circumference of said opening.
3. The method of claim 1, wherein the step of moving said testing
optical fiber within said testing zone comprises rotating said
testing optical fiber to change the coupling orientation between
said testing optical fiber and said light transmitting/receiving
structure.
4. The method of claim 3, wherein an angle of rotation of said
testing optical fiber is a ranged from 0 degree to 360 degrees.
5. The method of claim 1, wherein the shape of said testing zone is
a circle, a polygon, a ring, or an ellipse.
6. The method of claim 1, wherein said light transmitting/receiving
structure is an optical subassembly, an optical or optoelectronic
component, an optical package, an testing optical fiber, or a
transceiver module.
7. The method of claim 6, wherein said optical or optoelectronic
component is an LED, a semiconductor laser, or a photodiode.
8. The method of claim 6, further comprising judging the quality of
said testing optical fiber according to said variations when said
light transmitting/receiving structure is a standard optical
fiber.
9. The method of claim 1, wherein said variations are measured by
using an optical power measuring device.
10. An apparatus for testing for the quality of a light
transmitting/receiving structure, said apparatus comprising: a
securing structure, for securing said light transmitting/receiving
structure; a defining structure, having a testing zone being
coaxially positioned with a predetermined light
transmitting/receiving path in said securing structure; and a
testing structure, said testing structure having a testing optical
fiber, an end of said testing optical fiber being passed through
said testing zone and coupled to said light transmitting/receiving
structure.
11. The apparatus of claim 10, wherein said testing structure
further comprises an optical detector for measuring variations of a
strength of an optical signal transmitted by said light
transmitting/receiving structure.
12. The apparatus of claim 11, wherein said optical detector is
coupled to another end of said testing optical fiber.
13. The apparatus of claim 11, further comprising a light source,
said light source being coupled to another end of said testing
optical fiber.
14. The apparatus of claim 13, wherein said optical detector is
coupled to said light transmitting/receiving structure and is used
for measuring variations of the strength of an optical signal
received by said light transmitting/receiving structure.
15. The apparatus of claim 10, wherein said light
transmitting/receiving point coincides with the point of light
transmitting/receiving in said light transmitting/receiving
structure when being held by said securing structure.
16. The apparatus of claim 15, wherein said line and an extension
line from said light transmitting/receiving point to an edge of
said testing zone define a movement angle.
17. The apparatus of claim 16, wherein said movement angle is
ranged from 5 degrees to 13 degrees.
18. The apparatus of claim 15, wherein a maximum distance between
the circumference and the center of said testing zone divided by a
distance between said light transmitting/receiving point and the
center of said testing zone is in the range of 0.08 to 0.25.
19. The apparatus of claim 10, wherein the shape of said testing
zone is a circle, a polygon, a ring, or an ellipse.
20. The apparatus of claim 10, wherein said light
transmitting/receiving structure is an optical subassembly, an
optical or optoelectronic component, an optical package, an optical
fiber, or a transceiver module; and wherein said optical or
optoelectronic component is an LED, a semiconductor laser, or a
photodiode.
Description
RELATED APPLICATIONS
[0001] The present application is based on, and claims priority
from, Taiwan Application Serial Number 93104822, filed Feb. 25,
2004, the disclosure of which is hereby incorporated by reference
herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to testing for the quality of
a light transmitting/receiving structure. More particularly, the
present invention relates to a method and apparatus for testing for
the quality of a light transmitting/receiving structure by
determining whether the optical signal transmission path thereof
deviates or not.
[0004] 2. Description of Related Art
[0005] In the field of data communications, optoelectronic
transceivers act as the interface between electrical and optical
transmission media. Optical transmitters convert electrical data
signals into optical signals, which may be transferred over fiber
optic cables. Conversely, optical receivers receive optical signals
and convert them into electrical signals. Each optical transmitter
and optical receiver can be a separate device, or they may be
combined into a single device to form an optoelectronic
transceiver.
[0006] A key element of any optical transmitter or receiver is an
optical subassembly. In the case of an optical transmitter, an
optical subassembly may comprise a transmitting optical subassembly
(TOSA); while in the case of an optical receiver, an optical
subassembly may comprise a receiving optical subassembly
(ROSA).
[0007] Taking a TOSA as an example, the TOSA provides the physical
structure to couple the optical output signal of the transmitter to
an optical fiber and acts to align and focus the optical signal
onto the end of the optical fiber such that the optical signal
enters the optical fiber and is transmitted to a remote
location.
[0008] FIG. 1A illustrates the assembly of the components of a TOSA
to form a light transmitting/receiving structure. The TOSA 10
includes an optical package 20, a cylindrical holding barrel 26 and
a ferrule 30. The optical package 20 has an optical or
optoelectronic component 21. FIG. 1B is a magnified cross-section
of the ferrule 30. The ferrule 30 includes an axial hole 34, a
fiber stop 32, and a C-ring 36.
[0009] In traditional manufacturing processes, components of a
light transmitting/receiving structure have inherent flaws that
frequently cause deviations in the optical signal transmission path
of the structure after being assembled. The light
transmitting/receiving structure thus produced is of poor quality.
With respect to the TOSA 10, possible causes of deviations in the
optical signal transmission path include misalignment of the
optical axis of the optical or optoelectronic component 21,
improper location of a focusing element (not shown in FIG. 1A),
loose or slack connection between the optical package 20 and the
holding barrel 26, loose connection between the holding barrel 26
and the ferrule 30, failure of the C-ring 36 to firmly grasp the
optical fiber that is inserted into the axial hole 34, inadequate
core concentricity of the fiber stop 32, and failure of the ferrule
30 to firmly grasp the fiber stop 32. In light of these problems,
the quality of a finished or semi-finished light
transmitting/receiving structure product is likely to be poor. In
addition, the reliability of a finished or semi-finished product
cannot be controlled without a pretest mechanism, and consequently,
the product yield is uncertain.
SUMMARY OF THE INVENTION
[0010] It is therefore an objective of the present invention to
provide a method of testing for the quality of a light
transmitting/receiving structure to improve the reliability
thereof.
[0011] It is another objective of the present invention to provide
an apparatus for testing for the quality of a light
transmitting/receiving structure to ensure that the light
transmitting/receiving structure during manufacturing stages has
good quality and reliability.
[0012] It is still another objective of the present invention to
provide a method of testing for the quality of a light
transmitting/receiving structure so as to reduce the manufacturing
cost thereof.
[0013] Accordingly, the invention provides a method of testing for
the quality of a light transmitting/receiving structure. This
method includes the following steps. First, an end of a testing
optical fiber is coupled to the light transmitting/receiving
structure. The testing optical fiber and the light
transmitting/receiving structure are then fixed on a securing
structure, and the testing optical fiber is passed through a
testing zone, and the optical signal transmission path of the light
transmitting/receiving structure is coaxially positioned with the
testing zone. Next, the testing optical fiber is moved within the
testing zone, and variations of the strength of an optical signal
transmitted in the testing optical fiber are measured. Finally, the
quality of the light transmitting/receiving structure is judged
according to the variations.
[0014] The invention also provides an apparatus for testing for the
quality of a light transmitting/receiving structure. This apparatus
includes a securing structure, a defining structure, and a testing
structure. The securing structure is used to hold the light
transmitting/receiving structure. The opening of the defining
structure defines a testing zone, and the geometric axis of the
testing zone is coaxially positioned with a predetermined light
transmitting/receiving path in the securing structure. The testing
structure includes a testing optical fiber. An end of the testing
optical fiber is passed through the testing zone and coupled to the
light transmitting/receiving structure.
[0015] Advantages of employing the invention include the following.
During different manufacturing processes of a light
transmitting/receiving structure, performing the test method can
help to successfully and quickly determine whether the optical
signal transmission path of the light transmitting/receiving
structure deviates or not. By said method, a bad light
transmitting/receiving structure can be found and improved on time,
thereby the yield of the light transmitting/receiving structure can
be further increased. In addition, the test method can be performed
before, during, or after assembly of the components that comprise
the light transmitting/receiving structure; and therefore, the
quality of the light transmitting/receiving structure can be
monitored and maintained during every manufacturing stage in order
to increase product yield.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings
where:
[0017] FIG. 1A illustrates the assembly of components of a TOSA to
form a light transmitting/receiving structure;
[0018] FIG. 1B is a magnified cross-section of the ferrule in FIG.
1A;
[0019] FIG. 2 illustrates a configuration for performing the test
method of the invention;
[0020] FIG. 3 illustrates a partial apparatus used for testing a
light transmitting/receiving structure according to an embodiment
of the invention;
[0021] FIG. 4 illustrates a configuration for testing the quality
of the TOSA of FIG. 1A by using the partial apparatus of FIG.
3;
[0022] FIG. 5 illustrates the components of an exemplary holding
structure of the partial apparatus in FIG. 3; and
[0023] FIG. 6A-6D illustrate different shapes of the testing zone
defined by the opening of the defining structure of the testing
apparatus of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The present invention provides a method of testing the
quality of a light transmitting/receiving structure, which is
described below. The method is used to substantially increase the
quality and reliability of a light transmitting/receiving
structure. The light transmitting/receiving structure is the object
to be tested, and can be, for example, an optical subassembly, an
optical or optoelectronic component, an optical package, an optical
fiber, or a transceiver module. FIG. 2 illustrates a configuration
for performing the test method, the steps of which are described as
follows. First, an end of a testing optical fiber 202 is coupled to
a light transmitting/receiving structure 200. The testing optical
fiber 202 and the light transmitting/receiving structure 200 are
then fixed, and the testing optical fiber 202 is passed through a
testing zone, and the optical signal transmission path of the light
transmitting/receiving structure 200 is coaxially positioned with
the testing zone. Next, the testing optical fiber 202 is moved
within the testing zone. For instance, the testing optical fiber
202 is moved up and down or forward and backward, or moved around
the testing zone. Alternatively, the testing optical fiber 202 may
be rotated, which changes the coupling orientation between the
testing optical fiber 202 and the light transmitting/receiving
structure 200. Next, variations of the strength of an optical
signal transmitted in the testing optical fiber 202 are measured.
Finally, the quality of the light transmitting/receiving structure
200 is judged according to the variations.
[0025] The light transmitting/receiving structure 200 may comprise
an optical or optoelectronic component such as an LED, a
semiconductor laser (or laser diode), or a photodiode. In addition,
the securing structure described above may also comprise a holding
structure that is used to hold the light transmitting/receiving
structure 200. Furthermore, the variations of the strength of the
optical signal are measured by using, for example, an optical power
measuring device. In particular, when the light
transmitting/receiving structure 200 is a light transmitting
structure, the optical power measuring device is connected to the
testing optical fiber 202. When the light transmitting/receiving
structure 200 is a light receiving structure, the optical power
measuring device is connected to the light transmitting/receiving
structure 200, while the testing optical fiber 202 is connected to
a light source.
[0026] When the light transmitting/receiving structure 200
transmits an optical signal, a strength of the optical signal
transmitted from the light transmitting/receiving structure 200 to
the testing optical fiber 202 is measured. In order to judge the
quality of the light transmitting/receiving structure 200, a
tolerable error range in which the measured optical signal strength
variations should be set according to the strength of the optical
signal that is transmitted by the light transmitting/receiving
structure 200. If the measured optical signal strength approaches
the strength of the optical signal that is transmitted by the light
transmitting/receiving structure 200, and is within the acceptable
error range, the light transmitting/receiving structure 200 is
judged to be of good quality. On the contrary, if the measured
optical signal strength is not within the acceptable error range,
the light transmitting/receiving structure 200 is judged to be of
bad quality.
[0027] Furthermore, in order to assess the quality of the testing
optical fiber 202 itself, a standard testing optical fiber may be
used as the light transmitting/receiving structure 200, and the
testing method can be performed as described above.
[0028] According to an embodiment of the present invention, a
method is performed to test the TOSA 10, a light
transmitting/receiving structure, shown in FIG. 1A. FIG. 3
illustrates a partial apparatus used for performing the test. FIG.
4 illustrates a configuration for testing the quality of the TOSA
10 by using the partial apparatus shown in FIG. 3.
[0029] The partial apparatus in FIG. 3 includes a securing
structure 51 and a defining structure 60. The securing structure 51
further includes a holding structure 50 used for holding the light
transmitting/receiving structure. The physical shape of the holding
structure 50 depends on the shape of the light
transmitting/receiving structure. An opening 62 of the defining
structure 60 defines a testing zone, and the geometric axis of the
testing zone is coaxially positioned with a predetermined light
transmitting/receiving path in the securing structure 51. In this
embodiment, the shape of the opening 62 and the testing zone
defined by it is a circle. The testing apparatus further includes a
testing structure. The testing structure in this embodiment
comprises a testing optical fiber. An end of the testing optical
fiber may be connected to an optical detector or a light source.
The testing optical fiber is, for example, a standard testing
optical fiber or a calibrated optical fiber.
[0030] In addition, the shape of the testing zone defined by the
opening of the defining structure may be other shapes. The shape of
the testing zone may be a polygon, as exemplified by the triangle
and quadrilateral in FIG. 6A and FIG. 6B, respectively. The shape
of the testing zone may also be an ellipse or a ring as shown in
FIG. 6C and FIG. 6D, respectively. In FIG. 6D, the shape of the
testing zone defined by the opening of the defining structure is a
ring area 66 similar to a circular channel. The testing zone is not
necessarily a closed area.
[0031] Using the TOSA 10 as an example of a light
transmitting/receiving structure, the embodiment of the present
invention is further explained as follows. With reference to FIGS.
1A, 3, and 4, the TOSA 10 includes the optical package 20, the
cylindrical holding barrel 26, and the ferrule 30. A can-shaped
cover, called the TO can 22, of the optical package 20 covers the
optical or optoelectronic component 21. In this embodiment, the
optical or optoelectronic component 21 is a light-emitting
component, for example an LED or a semiconductor laser. An end of
the holding barrel 26 receives the optical package 20, and the
optical package 20 is fastened to the inside of the holding barrel
26 by a means such as gluing or welding. The other end of the
holding barrel 26 receives the ferrule 30, which is used to connect
and position an external optical fiber. The C-ring 36 shown in FIG.
1B inside the ferrule 30 is used for grasping the external optical
fiber. Additionally, the fiber stop 32 may be placed inside the
ferrule 30 to increase the usefulness and stability of the ferrule
30. In order to focus and reduce the loss of the optical signal
emitted by the optical or optoelectronic component 21 on an end of
the fiber stop 32, a focusing element may be used between the
optical or optoelectronic component 21 and the fiber stop 32.
Furthermore, the TOSA 10 usually connects to the external optical
fiber through a fiber optic connector 42. In this preferred
embodiment, a testing optical fiber 40 is used as the external
optical fiber.
[0032] As shown in FIG. 5, the holding structure 50 includes an
upper cover 54, a gripper 56, and a lower cover 52. The lower cover
52 has an engaging indentation 53 used for engaging with the TOSA
10. The gripper 56 has a hole 57 and two gripping arms 58. The TOSA
10 passes through the hole 57 and connects to the testing optical
fiber 40, while the two gripping arms 58 grip the fiber optic
connector 42 to secure the testing optical fiber 40 firmly. The
physical shape of the two gripping arms 58 depends on the shape of
the fiber optic connector 42. The upper cover 54 and the lower
cover 52 attach to, enclose, and secure the TOSA 10, the gripper
56, and the fiber optic connector 42. The components of the holding
structure 50 can be separately, partially assembled, or integrally
formed as a single piece. If the holding structure 50 is not
employed, other methods can be used to fix the testing optical
fiber 40 and the TOSA 10 on the securing structure 51. Also, when
the light transmitting/receiving structure itself can hold and
secure the testing optical fiber 40, the holding structure 50 can
be converted to have a shape suitable for holding the light
transmitting/receiving structure. In this case, the holding
structure 50 can have, for example, clasps and hooks.
[0033] With reference to FIG. 4, the predetermined light
transmitting/receiving point in the holding structure 50 coincides
with the point of light transmitting/receiving in the light
transmitting/receiving structure (TOSA 10) when being held by the
holding structure 50. In this case, a movement angle .theta. is
defined between a line from the point of light
transmitting/receiving to the center of the opening 62 and a line
extending from the point of light transmitting/receiving to an edge
of the opening 62. The movement angle .theta. can be specified as
needed and is preferably in the range of 5 degrees to 13 degrees.
In this embodiment, the movement angle .theta. is about 8.9
degrees. If the movement angle .theta. is larger, the external
mechanical force that can be tolerated by a light
transmitting/receiving structure with good quality is larger.
[0034] In another aspect, there is a maximum distance y between the
circumference and the center of the opening 62, and there is a
distance D between the point of light transmitting/receiving and
the center of the testing zone. The quotient when the maximum
distance y is divided by the distance D is in the range of about
0.08 to about 0.25. Changing the maximum distance y and/or the
distance D changes the ratio of the maximum distance y to the
distance D. In this embodiment, the distance D is 48 mm, the
maximum distance y is 7.5 mm; and therefore, the ratio is about
0.156. If the ratio is larger, the external mechanical force that
can be tolerated by a light transmitting/receiving structure with
good quality is larger.
[0035] The procedures of the testing method performed in this
embodiment are described in detail as follows. First, the testing
optical fiber 40 is coupled to the TOSA 10 to make an end of the
testing optical fiber 40 contact the fiber stop 32, in order to
make the optical signal transmission path of the TOSA 10 pass
through the fiber stop 32.
[0036] The testing optical fiber 40 and the TOSA 10 are then fixed
on the securing structure 51 by using the holding structure 50 of
the securing structure 51 to grasp the TOSA 10 and the fiber optic
connector 42. Simultaneously, the testing optical fiber 40 is
passed through the opening 62, which defines the testing zone, of
the defining structure 60 such that the optical signal transmission
path of the TOSA 10 is coaxially positioned with the testing
zone.
[0037] Next, the free end of the testing optical fiber 40 is
coupled to an optical detector. In this embodiment, the optical
detector is an optical power measuring device 64, which is, for
example, a power meter. Alternatively, when the TOSA 10 is replaced
with a different kind of light transmitting/receiving structure, a
light source may, if needed, be used instead of the optical
detector, or the optical detector and the light source may be used
together. In this case, the testing apparatus further includes the
light source. During the test, the light source is coupled to the
free end of the testing optical fiber and sends light into the
testing optical fiber. At the same time, the optical detector is
coupled to the light transmitting/receiving structure and is used
for measuring variations of the strength of an optical signal
received by the light transmitting/receiving structure.
[0038] Next, the testing optical fiber 40 is moved within the
testing zone, and variations of the strength of an optical signal
transmitted in the testing optical fiber 40 are measured. The
quality of the TOSA 10 is judged according to the variations. In
order to judge the quality of the TOSA 10, a tolerable error range
in which the measured optical signal strength variations can lie
should be set according to the strength of the optical signal
transmitted by the TOSA 10. If the measured optical signal strength
variations lie within the error range, the TOSA 10 is deemed to be
of good quality. Otherwise, the TOSA 10 is deemed to be of bad
quality.
[0039] Moving the testing optical fiber 40 within the testing zone
may include moving the testing optical fiber 40 up and down, right
and left, or forward and backward; or moving the testing optical
fiber 40 clockwise or counterclockwise around the circumference of
the opening 62. This manner of moving the testing optical fiber 40
while measuring the optical signal strength can in the main test if
the optical signal transmission path of the TOSA 10 deviates as a
result of applied mechanical force, which results in bad
quality.
[0040] Moving the testing optical fiber 40 within the testing zone
may alternatively include rotating the testing optical fiber 40 to
change the coupling orientation between the testing optical fiber
40 and the TOSA 10. This manner of moving the testing optical fiber
40 can in the main test for the concentricity of the TOSA 10 and
test if the optical signal transmission path deviates, which
results in bad quality. The angle of rotation of the testing
optical fiber 40 may be a ranged from 0 degree to 360 degrees.
[0041] The invention further includes a method for testing for the
quality of a testing optical fiber. In this method, a standard
optical fiber is used as the light transmitting/receiving
structure, and then the same steps as described above are performed
to test for the quality of the testing optical fiber before testing
another light transmitting/receiving structure, thereby validating
that the test method is accurate. When determining the quality of
the testing optical fiber, the standard optical fiber can be
arranged to transmit (or receive) an optical signal, and the
testing optical fiber is then arranged to receive (or transmit) the
optical signal. The quality of the testing optical fiber is then
judged according to the measured optical signal strength
variations.
[0042] It should be noted that the invention could be used to test
various kinds of light transmitting/receiving structure, such as an
optical subassembly, an optical or optoelectronic component, an
optical package, an optical fiber, and a transceiver module. The
optical or optoelectronic component may be an LED, a semiconductor
laser, or a photodiode.
[0043] Advantages of employing the invention include the following.
During different manufacturing processes of a light
transmitting/receiving structure, performing the test method can
help determine whether the optical signal transmission path of the
light transmitting/receiving structure deviates or not. When a
light transmitting/receiving structure with bad quality is
discovered by the test method, manufacturing processes can be
improved at once and in time to improve the quality of subsequently
manufactured light transmitting/receiving structures, thereby
increasing yield. In addition, the test method can be performed
before, during, or after assembly of the components comprising the
light transmitting/receiving structure such that the quality of the
light transmitting/receiving structure during every manufacturing
stage can be maintained and the product yield can be improved.
[0044] Although the present invention has been described in
considerable detail with reference to certain preferred embodiments
thereof, other embodiments are possible. Therefore, the spirit and
scope of the appended claims should not be limited to the
description of the preferred embodiments contained herein.
* * * * *